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1. The GMA950 video chip can change to match the ram/software requirements
2. Windows machines (non-Apple) with 2gb system ram can have a 224mb video card
3. Apple machines with the GMA950 are capped at 64mb

Furthermore, using the Sandra test suite, it reports the Intel Mini has 228MB of video ram in XP with 2GB of RAM installed.

Yeah, that'd be nice. It's kinda irrelevant for me since I already have a iMac with 256 MB video card, but for those who use the MacBook with an external monitor (or with certain apps), support for 128 MB (or more) would be a bonus.

Considering it makes sense for many to get 2 GB RAM for the MacBook anyway for dual-channel RAM support, it wouldn't hurt to lose an extra 64 MB of that for the video memory (on top of the 80 MB already used currently).

It would be very beneficial for someone like me who will be using the Macbook as my main computer. The thing that bothers me is the fact that under Windows, it can use up to 224mb RAM, but OSX is being a jerk and capping it at 64mb. I think it might be because the Macbook comes with 512mb stock, and then if the GMA took 224, that's not a lot of RAM left over, so the capping makes sense. Yet, even if you max out the RAM to 2gb, it's still capped at 64mb! Why the hell is that!?

Some people have speculated that Apple doesn't actually cap the GMA 950 at all, but just reports the minimum in System Profiler, no matter how much RAM is being shared.

But I decided not to get the MacBook, so I didn't look into that claim further. Civ IV runs well enough on my 12" PB.

IIRC, my 2 GB MacBook slows down in Exposé at around 15 open windows or so. That was very similar to my TiBook 1 GHz with Radeon 9000 64 MB. However, it was closer to 28 or so with my 20" iMac G5 with Radeon 9600 128 MB.

Thus, I think the 64 MB cap for the MacBook is probably real, regardless of the amount of RAM present in the machine.

Has anyone confirmed that the Intel Macs won't use more than 64MB system memory for VRAM? I understand that the system profiler will claim it's always 64MB, but has anyone checked another way to verify that it's not using more than 80MB?

Has anyone confirmed that the Intel Macs won't use more than 64MB system memory for VRAM? I understand that the system profiler will claim it's always 64MB, but has anyone checked another way to verify that it's not using more than 80MB?

Like I said (and I agree that this isn't perfectly scientific), my 2 GB MacBook starts to get jittery in Exposé with the same number of open Safari windows (15) as my TiBook with Radeon 9000 64 MB, while my G5 iMac with 128 MB can have almost twice the number (28) of open windows.

I opened over 40 windows with my iMac with 256 MB video RAM and there was still no jitteriness.

Like I said (and I agree that this isn't perfectly scientific), my 2 GB MacBook starts to get jittery in Exposé with the same number of open Safari windows (15) as my TiBook with Radeon 9000 64 MB, while my G5 iMac with 128 MB can have almost twice the number (28) of open windows.

I opened over 40 windows with my iMac with 256 MB video RAM and there was still no jitteriness.

I don't really see that as evidence.... could easily be limited by GPU performance or VRAM bandwidth rather than VRAM quantity.

Like I said (and I agree that this isn't perfectly scientific), my 2 GB MacBook starts to get jittery in Exposé with the same number of open Safari windows (15) as my TiBook with Radeon 9000 64 MB, while my G5 iMac with 128 MB can have almost twice the number (28) of open windows.

I opened over 40 windows with my iMac with 256 MB video RAM and there was still no jitteriness.

I don't think this can be the measure of anything. My iMac 20"CD 128mb had over 40 open and there was no sign of slowdown or jitter.

I don't really see that as evidence.... could easily be limited by GPU performance or VRAM bandwidth rather than VRAM quantity.

I agree, but I will note that I got the same results with my 64 MB Radeon 9000 (dedicated memory) and my 64 MB GMA 950 machine (shared memory).

Also, Exposé on an iBook with Radeon 9550 32 MB slows down much quicker. A Radeon 9550 is much faster than both the Radeon 9000 and GMA 950.

Originally Posted by kmkkid

I don't think this can be the measure of anything. My iMac 20"CD 128mb had over 40 open and there was no sign of slowdown or jitter.

For the purposes of the test, I stuck with Safari windows, open to the same web page. If I used smaller windows from other apps I could open more of them before the slowdown.

Anyways, I'm not saying my test is incredibly scientific. I'm just saying that there is absolutely no evidence out there that suggests there is any truth to the speculation that video RAM usage scales in OS X with amount of system RAM present. Apple system profiler says it's 64 MB regardless of the amount of RAM present, and I believe it.

OS X caps the GMA 950, but not totally. According to MacWorld, OS X can get more VRAM if needed from the 950. They didn't say how much.

If that's the case, Apple System Profiler doesn't report it. When I open enough windows to get Exposé to slow down significantly, ASP still reports 64 MB.

Anyways, so far we have no evidence that OS X changes video RAM size on-the-fly with GMA 950. Furthermore, Tim Boger of Apple said this for the Mac mini: The mini's graphics

Although on PCs the GMA950 can potentially eat up as much as 224MB of main memory for use in frame buffering, Boger told us that Apple’s implementation doesn’t work that way: on the new Mac minis, the GMA950’s memory use is locked at 64MB. In other words, graphics won’t eat up more than its allotted share of your RAM (which is actually 80MB, since in addition to the 64MB for graphics, 16MB is set aside for what Boger called “general setup of the system”).

The GMA 950 allocates a base amount of 80 MB for video and boot processes at startup. In a computer configured with 512 MB of SDRAM, this leaves 432 MB of SDRAM available to Mac OS X in a standard system (configured with 512 MB SDRAM).Mac OS X may make additional main memory available to the graphics processor for texture use beyond the base 80 MB amount mentioned above, depending on the application being used.

I think you all are confusing memory wired down at startup versus memory available to the graphics system while running the OS.

System Profiler says:
VRAM (Total): 64 MB of shared system memory

This is the base startup wired VRAM(always in use by the display chip), not the total that can be used by games, etc. As textures and the like are allocated, more system ram is used as vram for the display chip.

If you look through the ioregistry under the AppleIntelFramebuffer node under the graphics node you can see
ioreg -l | grep IOFBMemorySize
"IOFBMemorySize" = 268435456

One thing I noticed when using a Macbook with an external screen was that the second screen dropped a lot of frames when I had something spanning both screens (extended desktop mode). I don't know if this was related to the lack of VRAM or just the card being weak.

Just chiming in...I wrote the post linked in the OP. I haven't had any luck in uncapping the GMA950 in OS X. My friend and I have spent a great deal of time hacking the Mini; we have successfully created SATA and ATA adapters for using full-sized hard drives and optical drives, swapped a number of processors (Yonahs & Meroms), upgraded the ram/slim hard drive/slim optical drive, and so on. Still no luck on the GMA950. I believe that it IS possible with enough work, but when you get right down to it, what real benefit will doubling the ram on an already low-end graphics chip give you? I'd love to do it, but the cost-benefit ratio has been dwindling in the months since I started hacking the Mini. Just thought I'd post a little update

One thing I noticed when using a Macbook with an external screen was that the second screen dropped a lot of frames when I had something spanning both screens (extended desktop mode). I don't know if this was related to the lack of VRAM or just the card being weak.

Just curious, what if you are using the MacBook in clam shell mode and are only using the external screen. Does it still do that?

I see a lot of speculation here regarding the GMA950 and that is has been "capped" at only 64MB by Apple.

First a disclaimer: Although I work for Intel I am not a spokesperson for the company and my comments shouldn't be considered any sort of official company statement. During my day job I develop graphics drivers for Intel including the GMA950 series. However, I don't have any insight into Apple's device drivers. Similarly, everything included here is available from public sources and does not include any proprietary information.

What Apple is saying (and makes complete sense based on the architecture of the chipset) is that they allocate a minimum of 80MB of system memory for the GMA950 to use. Additional memory will be allocated as needed up until the maximum addressable size which is 256MB.

Put simply, there are two types of "things" that go into video memory:

1) The frame buffers
2) Textures/Surfaces

The GMA950 has a maximum resolution of 2048x2048 pixels with 32bpp color depth. That means a single frame buffer can take up to 16MB.

It can also display two unique images simultaneously. In the case of the Macbook, this means the internal LCD panel and the external DVI connector. Taking this into account we're up to 32MB -- in practice this will never happen since there really aren't any displays with that high a resolution on the market. However, Apple could be playing it safe and always reserve enough memory to handle all frame buffer sizes.

Similarly, Apple may be using the concept of having front and back buffers to provide smooth video. This means each display effectively has two frame buffers associated with it. As a result, now we're up to the magic 64MB number.

In addition to frame buffers, there are typically off-screen areas that are used to cache bitmaps, individual characters of fonts, the contents of a window that is going to be blitted or blended, etc.

There are countless uses for off-screen memory. Importantly though, the GMA950 can only off load work from the CPU when it has this memory to use. It can only accelerate drawing and compositing within video memory.

In this case, it sounds like Apple has ensured that there is a minimum of 16MB of off-screen memory for this use. As a result, we get the 80MB number.

The important thing to realize about integrated graphics chips such as the GMA950 is that memory can be dynamically moved from the system to the video processor at will. This is done in 4KB chunks up to the maximum address space of 256MB.

We already know from IOReg that Apple has configured the GMA950 with a 256MB aperture.

And Apple themselves have effectively confirmed all of this with their knowledge base article:

The Mac mini (Early 2006), MacBook and iMac (Mid 2006) computers use the Intel GMA 950 graphics processor for video output. This graphics chip set shares the main system memory of the computer rather than having dedicated graphics memory. The GMA 950 allocates a base amount of 80 MB for video and boot processes at startup. In a computer configured with 512 MB of SDRAM, this leaves 432 MB of SDRAM available to Mac OS X in a standard system (configured with 512 MB SDRAM).

Mac OS X may make additional main memory available to the graphics processor for texture use beyond the base 80 MB amount mentioned above, depending on the application being used. The most common types of applications that request more system memory to be used as graphics memory are 3D and graphics-intense applications.
Graphics Performance

For best graphics performance, your computer ships from Apple with two equal-sized SO-DIMMs installed, one in each slot. When memory is installed in your Mac in equal-sized pairs, the computer gains some performance benefits from the memory being interleaved. If you upgrade the memory in your Mac, make sure you have matching size SO-DIMMs (both in terms of memory size and in speed) in each slot for best graphics performance.

In short, the 64MB number being thrown around is a minimum value not a maximum value.

Thank you for that detailed explanation. Since it was all taken from public sources, I hope your Corporate Masters take a kind view to your involvement here, if they ever find out.

IIRC, I think the initial confusion stemmed from an early document about the mini's capabilities that stated the 64MB/80MB was a maximum, not a minimum. Either that document was in error, or Apple originally intended to cap the video memory, but backed off after seeing the reaction. Count me as someone who opted to buy a used 12" PB instead of a MacBook based (partly) on this information. While I'm happy that it isn't capped, Apple still lost a sale because of my confusion.

This all appears to be a lesson in how misinformation can take on a life of its own on the Internet!

I do a lot of work on my Mac Mini with video editing, and it works perfectly fine for everything I need. However, some applications don't care what's actually available to the GMA950, but only what it reports. For this reason, I can't use a number of Final Cut Pro filters (they say I need a video card with more memory alas) and Apple Color, the main tool I'm interested in, doesn't even install for the same reason.

If there is some way we could perhaps hack a kext or something to at least allow programs to "see" the extra memory available, that would be helpful in itself. If for example, system profiler would report 128MB instead of 64, then all these extra apps and tools would work. I think it's pretty much understood that the card is capable of doing it, (performance issues or not).